Note1: This ROM supersedes the (former) "FlashBack15" ROM as of 2010/10/20. This step was taken because it appears that VZW/Google are no longer providing Cupcake->Eclair OTA downloads for the Eris.

Note2: The V2 FlashBack21 ROM installs the stock HTC software corresponding to the March 2011 OTA version V2.41.605.6. The V1 FlashBack21 ROM installs the stock HTC software corresponding to the July 2010 OTA - version V2.37.605.4

Last Updated: March 06 2011

This ROM is intended for reverting a rooted Eris with a custom recovery to the HTC stock software: March 2011 2.1 OTA ROM - v 2.41.605.6. There are many other ways to do this; but this way uses Amon_RA for the installation as a convenience for less experienced rooters. (And only Amon_RA v1.6.2 - the installer will refuse to work with any other recovery.)

Two versions are provided: one which flashes the radio firmware version 2.42.01.04.27, and one which does not flash the radio; other than this difference, they are identical. (The same radio firmware - v2.42.01.04.27 - was used in both the July 2010 & March 2011 OTA releases.) Choose the ROM which best fits your needs. If you already have the most recent radio installed (2.42.01.04.27), there is no need to reflash the radio.

Derived from the Eris "March 2011 OTA" (2.41.605.6) release, this ROM repackages the last official 2.1 ("Eclair") release for the Eris from HTC/VZW so that it can be installed with Amon_RA recovery - you flash it just like any other dev ROM. There are essentially no customizations, and no built-in root or extra tools; it is 99.99% stock, with the following difference:

- This ROM also performs jcase's "Flash Any RUU" patch to the misc partition during the flashing process.

This step is performed so that the Eris responds well to flashing operations involving the use of any PB00IMG.zip file (via HBOOT), or application of any RUU utility for the Eris. So, even though this is an "unrooting" ROM, pains are taken to make sure that it is easy as possible to re-root or manipulate with existing methods.

This ROM does not touch the bootloader (or "Hboot" or "IPL/SPL"). If you want to install a different bootloader, do it first before applying this ROM.

Please Note: THE RECOVERY BOOT PARTITION IS REPLACED BY THE MATCHING VERSION OF THE STOCK RECOVERY PARTITION (V2: March 2011 OTA; V1: July 2010 OTA) in this ROM. This means that you will need to re-root your phone if you use this ROM, should you later decide that you want to restore a different ROM.

Please Note 2: ONE OF THESE ROMs FLASHES A RADIO. This is different than nearly 99% of all Eris dev ROMs. You will see some activity at the conclusion of your Amon_RA recovery session as a result of this - if you choose to use the ROM version that flashes the radio firmware.

Instructions

- Read this whole post all the way through before you begin
- Charge your phone completely
- Download the .zip file you need to the top-most folder of your SD card
- Verify the length and/or MD5 checksums (of the copy of the ROM file on the SD card)
- Boot into the Amon_RA recovery, Wipe, and then flash the FlashBack21 ROM (of your choosing)

IF YOU ARE FLASHING THE RADIO:
- When flashing is complete, you will see the message at the bottom of the screen:"Reboot via vol-up+vol-down or menu to complete installation"
- Make sure to exit Amon_RA after the ROM has finished flashing by selecting the "Reboot now" top-level menu item. Don't do something stupid like pulling the battery.
- You will see two successive splash screens that you do not normally see when using Amon_RA - these indicate that the factory recovery boot is performing the radio flashing operation. Do not interrupt - the phone will reboot on it is own when this step completes.

Acknowledgments

- Amon_RA for his recovery boot
- jcase for his disclosure to the Eris community of the misc partition "main version number" patch
- hundreds of others on XDA and AF too numerous to mention
- doogald for re-hosting the ROMs (2/15/2012)

- This is here for historical purposes only.
- Note this now ONLY provides a Cupcake (Android 1.5) Factory roll-back for the Eris, as VZW/Google are no longer providing OTAs for the Eris.
- Do not use unless you specifically want a stock "Cupcake" (Android 1.5) Eris
- Note this ROM also UNROOTS YOUR PHONE by replacing the custom recovery with the stock recovery

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